<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div{
            width: 100px;
            height: 100px;
            background-color: pink;
            position:absolute;
        }
    </style>
</head>
<body>
    <button>开始</button>
    <div>
        111
    </div>
    <script>
       function animate(obj,target){
        obj.timer = setInterval(function(){
            if(obj.offsetLeft>=target){
                clearInterval(timer);
            }
        obj.style.left = obj.offsetLeft + 1 + 'px';
        },30);
       }
       var div = document.querySelector('div');
        var btn = document.querySelector('button');
       
       
       btn.addEventListener('click',function(){
            animate(div,300);
       })
    </script>
</body>
</html>